Cytological Performance Evaluation of a Novel Skin-Repair Agent: Recombinant Protein Disulfide Bond Isomerase

To investigate the potential of recombinant protein disulfide isomerase (PDI) as a raw material for skin-repair cosmetics, an engineered PDI-producing strain was constructed using the Pichia pastoris X33 expression system. The target protein was obtained through methanol-induced expression and anion-exchange chromatography purification, and its cytotoxicity and pro-adhesive effects on human skin fibroblasts (HSFs) were evaluated. The results showed that the purified recombinant PDI protein had an apparent molecular weight of approximately 55.7 kDa. Treatment with 0.04-5 µmol/L recombinant PDI for 24 h did not affect cell viability. On culture surfaces coated with 62.5 nmol/L recombinant human fibronectin (rhFN) or 31.25 nmol/L recombinant human collagen (rhC), the addition of 250 nmol/L recombinant PDI increased the HSF adhesion area ratio to approximately 2.1-fold that of the rhFN-alone group (p < 0.0001) and 1.9-fold that of the rhC-alone group (p < 0.0001). Collectively, the recombinant PDI protein exhibits good biocompatibility and pro-adhesive activity, demonstrating its potential as a candidate raw material for skin-repair cosmetics.